Heart rate recovery in patients with hypertrophic cardiomyopathy
Vimal Patel1, Christopher H Critoph1, Malcolm C Finlay1
1Inherited Cardiac Diseases Unit, The Heart Hospital, University College London, London, United Kingdom.
Insights
Heart rate recovery (HRR) after exercise is impaired in patients with hypertrophic cardiomyopathy (HC). This reduced HRR correlates with the severity of left ventricular outflow tract obstruction, suggesting autonomic dysfunction in HC.
Area of Science:
- Cardiology
- Autonomic Function
- Exercise Physiology
Background:
- Heart rate recovery (HRR) after exercise reflects autonomic nervous system function and serves as a prognostic indicator in cardiovascular diseases.
- Hypertrophic cardiomyopathy (HC) is a condition affecting the heart muscle, potentially impacting autonomic regulation.
- Characterizing HRR in HC is crucial for understanding disease mechanisms and prognosis.
Purpose of the Study:
- To characterize heart rate recovery (HRR) in patients with hypertrophic cardiomyopathy (HC).
- To determine the relationship between HRR and cardiac function and morphology in HC patients.
- To investigate potential autonomic dysfunction indicated by HRR in HC.
Main Methods:
- Studied 41 patients with HC and 18 healthy volunteers.
- Utilized transthoracic echocardiography for cardiac assessment.
- Performed continuous beat-by-beat heart rate monitoring during and after cardiopulmonary exercise testing using finger plethysmography.
- Calculated HRR and power spectral densities from RR recordings.
Main Results:
- Patients with HC exhibited significantly lower absolute HRR at 1, 2, and 3 minutes post-exercise compared to controls.
- HRR remained lower in HC patients even after normalization to peak heart rate.
- Impaired HRR at 3 minutes was observed in obstructive HC compared to controls after normalization to rest-to-peak exercise heart rate difference.
- Heart rate at 3 minutes post-exercise correlated with peak left ventricular outflow tract gradient and predicted HRR in multivariable analysis.
- A trend towards increased sympathetic predominance (higher low-frequency to high-frequency ratio) was noted in HC patients.
Conclusions:
- Heart rate recovery is demonstrably impaired in individuals with hypertrophic cardiomyopathy.
- The degree of HRR impairment in HC is associated with the severity of left ventricular outflow tract obstruction.
- These findings suggest underlying autonomic dysfunction in HC, with potential prognostic implications.
- Further prospective studies are warranted to confirm the prognostic value of HRR in HC.
Abstract:
Recovery in heart rate (HR) after exercise is a measure of autonomic function and a prognostic indicator in cardiovascular disease. The aim of this study was to characterize heart rate recovery (HRR) and to determine its relation to cardiac function and morphology in patients with hypertrophic cardiomyopathy (HC). We studied 18 healthy volunteers and 41 individuals with HC. All patients underwent clinical assessment and transthoracic echocardiography. Continuous beat-by-beat assessment of HR was obtained during and after cardiopulmonary exercise testing using finger plethysmography. HRR and power spectral densities were calculated on 3 minutes of continuous RR recordings. Absolute HRR was lower in patients than that in controls at 1, 2, and 3 minutes (25.7 ± 8.4 vs 35.3 ± 11.0 beats/min, p <0.001; 36.8 ± 9.4 vs 53.6 ± 13.2 beats/min, p <0.001; 41.2 ± 12.2 vs 62.1 ± 14.5 beats/min, p <0.001, respectively). HRR remained lower in patients at 2 and 3 minutes after normalization to peak HR. After normalization to the difference in HR between peak exercise and rest, HRR was significantly impaired in individuals with obstructive HC at 3 minutes compared with controls. HR at 3 minutes correlated with peak left ventricular outflow tract gradient (B 0.154 beats/min/mm Hg, confidence interval 0.010 to 0.299, p = 0.037) and remained a significant predictor of HRR after multivariable analysis. Spectral analysis showed a trend toward an increased low-frequency to high-frequency ratio in patients (p = 0.08) suggesting sympathetic predominance. In conclusion, HRR is impaired in HC and correlates with the severity of left ventricular outflow tract gradient. Prospective studies of the prognostic implications of impaired HRR in HC are warranted.
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